Isomerization of hydrocarbons



july 23 1945- J. c. lvERsoN ISOMERIZATION OF HYDROCARBONS Filed May 30, 1942 NNW mEm mmmzm o23 lNvr-:NTOR

JOHN o. lv RsoN KMMZMQZOU ATTORNEY Patented July 23, 1946 ISOMERIZATION OF HYDROCARBONS John O. Iverson, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application May 30, 1942, Serial No. 445,145

13 Claims. l

carbon conversion reactions in addition to isomerization will take place in such treatments. As a result of these treatments the antiknock properties of the gasolines charged are improved by the sum total of the reactions taking place.

More specically the present invention is concernes with a mode of operation which involves closely cooperating steps, the process being particularly suitable for use in connection .Withgran-k ular metal halide catalysts of the Friedel-Crafts type such as aluminum chloride.

The isomerization of paraflin and naphthene hydrocarbons to producemore highly branched compounds or compounds with more condensed structure is becoming increasingly important in connection with petroleum refining. The isomerization of normal butane is important in view of the fact that isobutane is considerably more reactive than normal butane and can, for example, be more readily alkylated with oleiins such as butenes to produce octanes of high antiknock value.v Butenes formed by the dehydrogenation of isobutane yield octenes which When hydrogenated yield octanes of higher antiknock rating than those produced by subjecting normal butane to a similar series of steps. Normal butane generally occurs in larger amounts than isobutane so that its isomerization is frequently necessary if the greatest possible utilization must be made of the gaseous products from petroleum distilling and cracking operations. v

In the case of normally liquid hydrocarbon mix'- ilures such as straight run gasoline fractions either of close cut or rather WideV boiling range processes involving isomerization of paraffins are of denite Value in that the treated fractions have increased antiknock rating so that the process ovlTers a means of greatly improving the quality of gasolines Without the excessive losses frequently encountered when fractions are reformed by s 2. A Y strictly thermal or high temperature thermalcatalytic methods. v

The isomerization of parain hydrocarbons is more or less readily brought about by lContact with such metal halides as aluminum chloride and aluminum bromide. Alternative metal halides not necessarily of equal efficiency include zirconium chloride, zinc chloride, ferric chloride or their bromides, or mixtures of these With each other or With aluminum halides. These halides may be used in a variety of Ways for the isomerization of hydrocarbons. One of the oldest and simplest methods consists in rellluxing the liquid in the presence of granular and finely `divided metal halides preferably With the addition of small amounts of Water or hydrogen halide, the lower boiling isomerv being taken overhead and condensed. Other methods employ aluminum` chloride, for example, supported on `relatively inert granular materials over which the hydrocarbon or hydrocarbon mixture to be isomerized is passed in liquid or vapor phase along with the hydrogen halide. More recent developments in continuous processes have involved the passage of hydrocarbons to be isomerized through beds oi granular aluminum chloride and the further passage of the hydrocarbon containing dissolved or entrained aluminum chloride into a reactor after the addition of a hydrogen halide. In a packed reactor, this operation serves to maintain a definite amount of active metal halide on the surface of the packing. The present process is concerned with improvements in this type of operation so that some of the operating diii'culties commonly encountered are obviated.

In one specic embodiment as applied to normal butane representing saturated isomerizable hydrocarbons the present invention comprises passing said normal butane and hydrogen chloride through a stationary bed of granular aluminum chloride under a temperature and pressure adequate to effect isomerization while simultaneously introducing a portion of the cooler normal butane charge at spaced points in the aluminum chloride bed to control undue temperature rise therein, passing the products from the aluminum-chloride contact into contact with granular absorbent material for the removal of aluminum chloride contained in products While introducing further amounts of cooler butane charge at spaced points in the absorbent material to control temperature therein, fractionating the products from contact with the absorbent to produce hydrogen chloride,v

isobutane and normal butane, recycling said hydrogen chloride to commingle with normal butane charge, recovering said isobutane and recycling said normal butane to further isomer- Vizing treatment.

` l Wardly through a reaction zone by lan ascending stream of vapors of hydrocarbons followed by separation of hydrocarbons and powdered catalyst with return of the latter yto further catalytic use either with or without intermediate regeneration.

The features of the present invention and particularly the use of relatively cool charge to control temperature in theisomerizing zones will be more fully described in connection with the a+- tached drawing which shows diagrammatically by the use of conventional gures in general side elevation an arrangement of apparatus in which the'process may be conducted. The description of the operation'is given in connection with the treatment of normal lbutane in the interest of simplifying the description and making it more I readily understandable though it is to be understood that a similar characteristic flow may be used on other individual hydrocarbons or on hy- 1 drocarbon4 mixtures particularly those represent- 3 ed by 'hydrocarbon fractions of gasoline boilingv range.

Referring to the drawing normal butane is introduced to the plant b-y Way of line I containing Valve 2 leading t0 a charging pump'3 which discharges through line 4 containing valve 5. Re-

cycled normal butaneenters line I from line |23 containing valvev I'24 as will be subsequentlydescribed. In accordance lwith the present invener'izing plant is'heated and passed to contact with granular aluminum chloride while a minor i portion is reserved .for effecting cooling in the l through a suitable heater 8 in which the charging material is brought to an optimum temperature for its isomerizing treatment. Unheated portions of 'the charge are passed through line 2| containing valve 22, and line 53 containing valve 54 for cooling purposes as will be described 1in proper sequence. Provision is made for passing a portion of the original charge through a secondary heater 5I in line 5I so that this portion of the charge may carry additional heat to the stream of hydrocarbon material from the `catalyst supply chambers I3 and I4 and permit substantially vapor phase operation in the reaction chambers 45 and 46 while a substantial amount 'ofxliquidphase ismaintained in the catalyst supply chambers.

The embodiment ofthe invention contemplates 1the use of lisomerizing reactors either in parallel, series or series-parallel connection. `parallel operation of reactors containing alumi- ThuS, in

num chloride the portion ofV the heated. Charge passes through line 9 containing valve I0 and line 9 containing Valve Ill' to -contact with granular aluminum chloride contained in catalyst tion `the `main portion ofthe char-ge to the isomeither raw or acid treated, kieselguhr, etc,

chamber I3 while a substantially equal portion passes through line I I containing valve I2 into and through the granular catalyst contained in catalyst chamber I4. In this strictly parallel operation of the two catalyst chambers the'eiiluent materials `from chamberfIS pass through line I5 containing valve I5 while those from chamber I4 pass through line I1 containing valve I 8, the streams combining in line I9 containing valve 2D and passing to Vthe succeeding chambers containing granular material. In case it is desired to .operate the twocatalyst chambers in series, the -eiliuent materials from chamber I3 may be 'di- Verted through line 33 containing valve 34 with valve I6 lclosed and pass through line 31 containing .valve .38 through line 25 containing valve 25 and leading to line I I and thence through chamber I4 with valves 36 and 24 closed so that the total eiuent materials passthrough line I] containing valve I8 to line I9. When chamber I4 is to be used as the rst ofthe series the chargev is introduced through line I I containing Valve ,I2 with valve 25 closed and the eliuent materials from chamber I4 pass through line 35 containing valve 3S with valves I8 and 34 closed and thence through line 31 containing valve 38 to line 23 containing valve 24 and into catalyst chamber I3 by way of line 9 with valve I 0" closed. The eluent materials in this case pass through line I5 containing valve I6 with valve 34 closed into line I 9.

To eiiect cooling of the reaction zones an unheated portion of the charge passes through line 2i containing Valve 22 and may be then passed through line 2l containing valve 28 to intermediate points ,in the `catalyst chambers by way of line 29 containing valve 39 and leadingv to catalyst chamber I3 or line 3| containing valve 32 and leading to catalyst chamberk III. The cooling or quenching fluid is .shown as being introduced at one `single point in each chamber although it is comprised within the scope of the invention to introduce the .cooling material at any point or plurality kof points which are found necessary to produce the best results. To provide for intermediate cooling between chambers when they .are used in series, a regulated portion of -cooling fluid may .be introduced either through valve 2I .into line 23 :or line 25 with valve 28 closed.

In the second stage of the isomerizing process the partially isomerized materials lfrom the rst zone in which they were contacted with aluminum chloride are passed to a secondary treating zone containing granular and preferably absorbent material such as, for example, porous refractories, granular aluminas, such as bauxite clays In Ithis stage further isomerizing action may occur as the partially converted hydrocarbons contact the absorbent which has taken up any aluminum chloride .carried over from the rst zone and at the same time metal halide-hydrocarbon complexes are absorbed and removed from the reaction products. of the process products of the primary isomerizing zone pass through line I9 and valve 20 into chambers containing granular absorbent material, these chambers being used in parallel, se-

Thus, in the ordinary operation` troduction our unheatedcharge. produc-tsv ing valve 44 to packed' chamber 46. ,A line' 39 containing valve 40 is also provided for the diversion or bypassing of a portion of the original heated charge to the secondary reaction chambers as a means of temperature control therein.

When chambers 45 and 46 are operating in parallel, the efliuent materials from chamber 45V will follow line 41 containing valve 48 while those from -chamber 46 follow line 49 containing valve 50, the two streams uniting in line containing valve 1| and passing to the succeeding fractionating zone. When the packed chambers are utilized in series with chamber 45 as the nrst chamber the effluent materials from this chamber will pass from line 41 through line 64 containing valve 65 with valves 48 and 61 closed and follow line 68 containing valve 69 and line 56 containing lvalve 51 to enter line 43, withvalves 44 and 55 closed. When chamber 46 is to be used as the first in a series the eilluent materials will pass from line 49 through line 66 containing valve 61 with valves 50 and 65 closed and through line 68v containing valve 69 to now through line 54' and valve 55 into line 4| with valves 42 and 51 closed. In this case the total effluent materials will pass through line 41 containing valve 48 into line 16.

For cooling purposes in the secondary zone containing granular material line 5I containing valve 52 leading through heater 5|" and line 5|' containing valve 52 serve to admit heated 0r cooler charge to line 4| or line 43. Line 53 containing valves 53 and 54 permits the passage of cooling fluid to line 58 containing valve 59 which has branch lines 6|] containing valve 6| leading to an intermediate point in chamber 45 and branch line 62 containing valve 63 leading to an intermediate point in chamber 46. Again these single points of introduction are merely to illustrate any single or any multiple points which may be used as circumstances may require. To permit intermediate cooling between charnbers when they are used in series line 53 leads to both line 54 containing valve 55 and line 56 containing valve 51.

In the preceding description the ilow through the catalyst chambers and packed chambers has been indicated as being upward but dovvnflows may also be used without departing from the scope of the invention.

The preferred arrangement of the isomerizing zones permits considerable exibility in operation. Thus the major amount of isomerization may be brought about in the primary zones designated as catalyst chambers in contact with granular aluminum chloride catalyst in the presence of hydrogen chloride; or the aluminum chloride in the primary zone may serve in the absence of added hydrogenI chloride merely as a source of supply of catalytic material to be deposited on granular materials in the second zones designated as packed chambers,` towhich hydrogen chloride is introduced to assist in the isomerizing action. The choice of operating procedure will depend upon the character of the hydrocarbon or hydrocarbon mixture which it is desired to isomerize. Similarly both temperature, pressure and flow rate may be varied in the primary and secondary zones so that substantially vapor phase conditions may be made to obtain in both zones, liquid phase conditions in both zones or liquid phase in the primary zone andvapor phase in secondary zone.' In the caseof normal butane satisfactory isomerization may be effected in theI `setup of the present character by passing the" normal butane through the aluminum chloride catalyst chambers in substantial liquid phase and eiecting isomerization in the succeeding secondary zone in vapor phase. In the case of normally liquid isomerizable hydrocarbons substantially liquid phase conditions may be maintained throughout the primary and secondary zone. In the case of normal butane temperatures of from approximately 150 to 200 F. may be maintained in the primary zone under pressures ofthe order of 250 to 350 pounds per square inch while slightly higher temperatures of the order vof 200 to 220.D F. and the same or slightlyA lower pressure ls used in the second zone.. The amount of hydrogen chloride present at any stage of the isomerization may be varied to control the rate and character of the reactions. of from about 1 to about 20 mole per cent of hydrogen chloride in respect to the hydrocarbon or hydrocarbon mixture undergoing isomerization may be used.

Following the isomerization stages the products are fractionated to recover those of desired char.

acteristics, hydrocarbon recycle stocks and hydrogen chloride. Thus, the total products from the secondary isomerizing zone may be caused to pass through condenser 'l2 wherein substantially complete liquefaction of all products isy obtained and the liqueed material passes through line 13 containing valve 14 to a receiver 15 provided with a gas release line`16 containing a valve 11 for theremoval of uncondensedgases.

In the next step the hydrogen chloride is recovered for reuse by a convenient means such as distillation under relatively high pressures above 300 and usually of the order of 450 pounds per square inch. Thus'a pump 80 takes suction on the liquid material in receiver 15 by way of line 18 containing valve 19 and discharges through line 8| containing valve 82 into a high pressure fractionating column 83 containinga plate 84 dividingthe lower section from the small upper section. The vapors of hydrogen chloride andv valve 92 to line 93 leading to line 6 and thence to the primary isomerizing step. Hydrogen chloride suicient to make up any incidental losses in the processing is admitted from line 93 containing valve 94 as required.

To provide for operation in which hydrogen n chloride is admitted only to the packed reaction chambers line 9 containing valve 92' is provided to permit the recirculated hydrogen chloride and any hydrogen chloride introduced from iline 93 to be introduced into line 5| ahead of Secondary heater 5| and thence to the packed chambers.

The bottoms from fractionator 83 pass through line 95 and a cooler 95' and are then split into a stream passing through line 96 and valve 91 and leading to line 10 to increase the'amount of liquid and promotev more effective condensation in condenser 12. `The main stream of bot- As a rule, amounts toms.. isfpassed. through. line 90 .containing valve. 90 to'l a' treating stagedesignated as |00 where |03 pass through line |04 containingr valve |05 and are liquefied during passage through condenser |06 after which `they pass through line I06 to a. receiver |01. To assist in controlling the fractionation in fractionator |03 a controlled portion of the condensed liquid. is returned to a point `near the top of the fractionator by a pump ||Il which takes suction in on line |08 by way of lineIIlS and discharges through line con.-

Vtaininglvalve ||2, the main portion of the iso.-

butane as a product of the process following line |08 and valve |09 to storage or use in other processes.

The bottoms from fractionator |03 consisting largely of normal butane together with some heavier hydrocarbons pass through line I3 containing valve I4 to a fractionator ||5 operated to effect the separation of normal butane. Thus the vapors of this compound pass through line I I6 containing valve I andare liqueiied by passage through condenser IIB after which they flow through line ||8 to a receiver ||9. Again to assist in controlling the fractionation in fractionator pump |25 takes a portion of the liquid from receiver ||9 by way of line |20 and line |20' and discharges it through line |26 containing valve |21 into a point near the top of the fractionator. The production of normal butane follows line |20 containing valve |2| to recycle pump |22 which discharges through line |23 containing valve |24 into line I to commingle with the fresh charge. Hydrocarbons heavier than normal butane are withdrawn as bottoms from fractionator I5 through line |28 and through a. condenser |29 and are then removed through line |30 containing valve |3| to a suitable storage. f

The following example is given to show typical charge rates, yields and operating conditions used in a process of the present character though without the intent of correspondingly limiting the scope of the invention.

The process is used to isomerize normal butane and the-total combined feed to the process including fresh and recycled butane is 1,078 barrels per day. 0f this materialr 269 barrels are preheated to a temperature of 190 1*". and passed in series through catalyst Supply chambers containing granular aluminum chloride. 695 barrels of the combined feed and 14,600 pounds of hydrogen chloride are passed through the main heater preceding the packed reaction chambers and heated to a temperature of 275 F. 114 barrels per day of the combined feed at a temperature of 157 F. is injected into the reactors which are used in parallel to oii'set the tendency toward temperature rise due to the exothermic character of the i'somerizing reaction. A pressure of 250 pounds per square inch is maintained upon both the saturators and the reactors and the hourly liquid space velocity per volume of reactor packing is 0.25. In operating in this 2&4045499,

mannerA with Y an overall. yield of; riso-,butane from.z normal butane of perk cent,"V the plant pro-. v

f5`20barrels of iso-butane per duces4 a yield of stream day.

I claim as my invention:

l. A process for the isomerization of normal butane which comprises passing a portion of a normal butane charge mixed with hydrogen chloride through a stationary bed of granular aluminum chloride ata temperature and pressureV adequate to effect isomerization while simultaneously introducing vfurther portions of the normal butane chargent spaced points in the aluminum chloride bed to control the temperature therein, passing the products from the aluminum chloride bed'into contact with granular absorbent material while introducing further portions of the butane charge at spaced points'` in the absorbent material. to control the temperature therein, fractionating the products resulting from contact with the absorbent to recover hydrogen chloride, isobutane and normal butane, recycling said hydrogen chloride to commingle with the normal butane charge, recovering said isobutane and recycling said norma butane to further isomerizing treatment. f

2. A process for the isomerization of normal butane which ,comprisesr passing. a portion of a normal butane charge mixed with hydrogen chloride through a stationary bed of granular aluminum chloride at a temperature of from about to about 200 F. and a pressure of from about 250 to about 350 pounds per squarev inch to effect isomerization while simultaneously introducing further portions of the normalV butane charge at spaced points in the aluminum chloride bed to control temperature therein, passing the products from the aluminum chloride bed into contact with granular absorbent material at a temperature of from about 200 .to .abouttroducing further portions of the butane chargeV at spaced points in the material to control tem.- perature therein, fractionating the products from contact with the absorbent under a pressure sub-- stantially in excess of 300 pounds per square inch to recover hydrogen chloride, isobutane and normal butane, recycling said hydrogen chloride to commingle with the normal butane charge, recovering said isobutane and recycling said normal butane to furtherisomerizing treatment.

3. A process for the isomerization of normal butane which comprises passing a portionof a normal butane charge mixed with hydrogen chloride through a stationary bed of granular aluminum chloride at a temperature of from about 150 to about 200 F. and a pressure of from about 250 to about 350 pounds per square inch to effect isomerization while simultaneously introducing further portions of the normal butane charge at spaced points in the aluminum chloride bed to control temperature therein, passing the products from the aluminum chloride bed into contact with granular absorbent material at a temperature ofv from about 200 to about 220 F. while introducing further portions of the butane charge at spaced points in the absorbent material to control temperature therein, fractionating the products from contact with the absorbent under a pressure substantially in excess of 300 pounds per square inch to recover hydrogen chloride, isobutane and normal butane, recycling said hydrogen chloride to commingle with the normal butane charge, lrecovering said isobutane and recycling said normal butane to further isomerizing treatment.

4. A process for the isomerization of normal butane which comprises passng a portion of a normal butane charge mixed With hydrogen chloride through a stationary bed of granular aluminum chloride at a temperature of from about 150 to about 200 F. and a pressure of from about 250 to about 350 pounds per square inch to effect isomerization with a substantial amount of said butane in liquid phase While simultaneously introducing furtherV portions of the normal butane charge at spaced points in the aluminum chloride bed to control temperature therein, passing the products from the alumium chloride bed into contact with granular absorbent material at a temperature of from about 200 to about 220 F. and under a, pressure corresponding to substantially vapor phase conditions while introducing further portions of the butane charge at spaced points in the absorbent material to control temperature therein, fractionating the products from contact with the absorbent under a pressure substantially in excess of 300 pounds per square inch to recover hydrogen chloride. isobutane and normal butane, recycling said hydrogen chloride to commingle With the normal butane charge, recovering said isobutane and recycling said normal butane to further isomerizing treatment.

5. A process for the isomerization of a normal paraiiin hydrocarbon which comprises passing a portion of the charge of said hydrocarbon mixed with hydrogen chloride through a stationary bed of granular aluminum chloride under a temperature and a pressure adequate to eiect isomerization while simultaneously introducing further portions of the hydrocarbon charge at spaced points in the aluminum chloride bed to control temperature therein, passing the products from the aluminum chloride bed into contact with granular absorbent material while introducing further portions of the hydrocarbon charge at spaced points in the absorbent material to control temperature therein, fractionating the products from contact with the absorbent to separate hydrogen chloride, a lower boiling isomeric hydrocarbon fraction and unconverted normal parailn hydrocarbon, recycling said hydrogen chloride to commingle with the paraffin hydrocarbon charge, recovering said isomeric fraction and recycling said unconverted paraffin hydrocarbon to further isomerizing treatment.

6. A process for treating a gasoline fraction composed predominantly of saturated hydrocarbons to increase the antiknock Value of said fraction which comprises passing a portion of said fraction mixed with hydrogen chloride through a stationary bed of granular aluminum chloride under a temperature and a pressure adequate to eiect a substantial increase in the antiknock value thereof While simultaneously introducing further portions of said fraction at a lower temperature at spaced points in said bed to control temperature therein, passing the products from the aluminum chloride bed to contact with granular absorbent material While introducing further portions of said fraction at a lower temperature at spaced points along the line of flow through the absorbent material tocontrol temperature therein, fractionating they products from contact with the absorbent to separate hydrogen chloride, a treated fraction of improved antiknock value and a higher boiling fraction, recycling said hydrogen chloride to commingle with the charge, recovering said treated fraction andV recycling said higher boiling fraction to further treatment. Y

'7. A process for isomerizing saturated hydrocarbons which comprises heating a portion of the saturated hydrocarbon charging stock to isomerizingtemperature, passing the thus heated hydrocarbons' together with a hydrogen halide v through a stationary bed of granular metal halide isonierizing catalyst under isomerizing conditions, simultaneously introducing another portion of said charging stock to at least one intermediate point of said bed to control the temperature in the bed, passing the products from the catalyst bed hrough a body of solid absorbent material while introducing an additional portion of said charging stock to at least one intermediate point of said body to control the temperature therein,

and fractionating the products discharging from said body to separate isomerized hydrocarbons therefrom,

3. A process for isomerizing paraiiinic hydrocarbons which comprises heating a portion of the paraiiinic hydrocarbon charging stock to isomerizing temperature, passing the thus heated hydrocarbons together with a hydrogen halide through a stationary bed of'granular metal halide isomerizing catalyst under isomerizing conditions, simultaneously introducing another portion of said charging stock to at least one intermediate point of said bed to control the temperature in the bed, passing the products from the catalyst bed through a body of solid absorbent material while introducing an additional portion of said charging stock 'to at least one intermediate point of said body to control the temperature therein, and fractionating the products discharging from said body to separate isomerized hydrocarbons therefrom 9. The process as defined in claim 7 further characterized in that said chargingstock comprises a naphthene hydrocarbon.

10. The process as dened in claim 7 further characterized in that said catalyst comprises an aluminum halide.

11. The process as defined in claim 8 further characterized in that said catalyst comprises an aluminum halide.

12. The process as deiined in claim 7 further characterized in that said catalyst comprises aluminum chloride and in that said hydrogen halide in hydrogen chloride.

13. The process as defined in claim 8 further characterized in that said catalyst comprises aluminum chloride and in that said hydrogen halide is hydrogen chloride.

JOHN O. IVERSON. 

